Results 201 to 210 of about 7,051 (253)
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Lithos, 2013
Abstract Metasomatic rocks, in which mineralogical change is driven by infiltration of an externally-derived fluid, are challenging for the application of equilibrium thermodynamics because fluid-driven changes in rock bulk composition can be faster than diffusive within-grain re-equilibration.
Katy Evans, R Powell
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Abstract Metasomatic rocks, in which mineralogical change is driven by infiltration of an externally-derived fluid, are challenging for the application of equilibrium thermodynamics because fluid-driven changes in rock bulk composition can be faster than diffusive within-grain re-equilibration.
Katy Evans, R Powell
exaly +3 more sources
Chemical aspects of hydrothermal alteration with emphasis on hydrogen metasomatism
Economic Geology, 1964The ratio of cation to hydrogen-ion concentration is used as a basis for coordinating many observed varieties of silicate rock alteration. Low ratios drive alteration from feldspar through sericite, montmorillonite, or paragonite, toward kaolinite or pyrophyllite.
J. J. Hemley, W. R. Jones
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Mineralogical zonation and metasomatism of the alteration pipes of Cyprus sulfide deposits
Economic Geology, 1989The stockwork mineralized lavas associated with the cupriferous pyrite deposits of Cyprus occur in the cores of concentrically zoned alteration pipes. These represent the channels of ascending hydrothermal solutions. This paper reports a detailed mineralogical and geochemical study of the Pitharokhoma alteration pipe and reconnaissance studies of other
H. G. Richards, J. R. Cann, J. Jensenius
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Magnesium metasomatism during hydrothermal alteration of new oceanic crust
Geology, 1978A semiquantitative calculation of the amount of Mg fixation during greenschist-facies metamorphism of a 1-km-thick section of the oceanic crust beneath mid-ocean ridge crests shows that it is of the same order of magnitude as the “excess” (unbalanced) input of this element to the ocean.
Salman Bloch, Albrecht W. Hofmann
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Geochemical features of metasomatically altered granitic rocks in Azov region
International Geology Review, 1967Mineralogical and chemical analyses, distribution-abundance of Li, Rb, Ta, Nb, Be, Sn, Zr and rare earths of granitoid massifs and migmatites, and other data show that the altered granitoids in the area are essentially transitions from lithionite-amazonite-biotite to biotite-albite apogranites representing early stages of the metasomatic process. --IGR
I.K. Pyatenko +2 more
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Metasomatically altered peridotite xenoliths from the hessian depression (Northwest Germany)
Geochimica et Cosmochimica Acta, 1990Abstract A set of 36 spinel lherzolite and spinel harzburgite xenoliths from 7 occurrences of Tertiary alkali olivine basalt and olivine nephelinite have been investigated for modal composition, major elements, and 39 minor elements. The peridotites were depleted during former partial melting events.
Gerald Hartmann, K.Hans Wedepohl
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Metasomatic Alteration of Ultramafic Rocks
1989Metasomatized ultramafic rocks from the 3800 Ma Isua supracrustal belt have been preferentially enriched in calcium, aluminium and silica, but show no or only little addition of potassium and rubidium. This unusual geochemical response to fluid infiltration can be explained in the light of a low buffered activity of aqueous silica during progressive ...
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Metasomatism in Iceland: Hydrothermal Alteration and Remelting of Oceanic Crust
1987The geochemistry of Icelandic volcanics, especially as pertains LIL-elements, RE-elements, and isotopes, has in the literature called for explanations involving heterogeneous mantle source. These explanations are shown to be incompatible with the data at hand.
S. Steinthórsson +3 more
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Combination processes of diamond recovery from metasomatically altered kimberlite rocks
Journal of Mining Science, 2017The article gives new experimental data on chemistry, phase composition, structure and physicochemical properties of surface of minerals composing metasomatically altered kimberlite rocks. The authors have determined formation conditions and basic genetic types of mineral micro- and nano-size phases on diamond surface in the form of aluminosilicate ...
V. A. Chanturia +5 more
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Geochimica et Cosmochimica Acta, 2022
Whether auriferous hydrothermal fluid is generated during crustal metamorphism or by subcrustal processes to form orogenic gold deposits is hotly debated. Noble gas isotope and halogen abundance ratios can provide important constraints to help resolve this controversy.
Hesen Zhao +5 more
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Whether auriferous hydrothermal fluid is generated during crustal metamorphism or by subcrustal processes to form orogenic gold deposits is hotly debated. Noble gas isotope and halogen abundance ratios can provide important constraints to help resolve this controversy.
Hesen Zhao +5 more
openaire +2 more sources